Shadblow Serviceberry – Amelanchier canadensis

ACS or Acs may refer to:

Organizations and societies

American Cancer Society, an American voluntary health organization dedicated to eliminating cancer
American Ceramic Society, an American professional organization
American Cheese Society, a professional organization of the American cheese industry
American Chemical Society, an American professional association
American College of Surgeons, a fellowship of American surgeons
American Colonization Society, an organization that helped in founding Liberia as a colony for freed slaves
American Constitution Society for Law and Policy, an organization of lawyers and law students in the US
American Cryonics Society, non-profit corporation that supports and promotes research and education into cryonics
American CueSports Alliance, a US-based pool league
Association of Caribbean States, an advisory, consultative body of Caribbean countries
Association of Cricket Statisticians and Historians, an association founded England in 1973 to collect cricket data
Audience Council Scotland, a BBC Trust organisation in Scotland
Australian Cinematographers Society
Australian Computer Society, an association for information and communications technology professionals
Australian Cricket Society, an association of cricket lovers
Redfern Aboriginal Children's Services, a community services organisation for Indigenous children in Sydney, Australia

ACS:Law, a British law firm specializing in intellectual property cases
Advanced Card Systems, a Hong Kong-based developer of smart cards and smart card readers
Advanced Composites Solutions, a Brazilian engineering company specialized in composite materials technology
Advanced Contact Solutions, a Philippine business process outsourcing company
Affiliated Computer Services, an American business and technology outsourcing company
Air Cess, a cargo airline based in Sharjah, United Arab Emirates
Alaska Communications System, former name of AT&T Alascom, an American communications services company
Alaska Communications Systems, an American communications services company, distinct from AT&T Alascom
Alternative compensation system, a way to allow reproduction of digital copyrighted works while still paying the authors and copyright owners
Applied Communication Sciences, a telecommunications research, engineering and consulting company based in the US
Grupo ACS (Actividades de Construcción y Servicios), a civil engineering firm based in Madrid, Spain

ACS-1 and ACS-360, supercomputers designed but never completed in the 1960s by the IBM Advanced Computing Systems
Access Control Service, a cloud-based service for authentication and authorization
Access Control Server, a component of Cisco's Network Admission Control technology
Access Control Server, the server authenticating a card in the 3-D Secure framework
Action Code Script, a scripting language used in video games such as Hexen: Beyond Heretic
Adobe Creative Suite, a software package by Adobe Inc.
Atacama Large Millimeter Array ("ALMA") Common Software, a control framework used in ground-based astronomy projects
Audit Collection Services, a component of Microsoft System Center Operations Manager

ACS International Schools, a group of international schools in the UK
Advanced Communicator, Silver ("ACS"), Toastmasters International Recognition for advanced Communication training
Alabaster City Schools, a school district headquartered in Alabaster, Alabama
Alperton Community School, a secondary school in London, UK
American College of Sofia, a secondary school in Sofia, Bulgaria
American Community School at Beirut, an international private school located in Beirut, Lebanon
American Community School in Amman, an international school in Amman, Jordan
American Community School of Abu Dhabi, an international school of Abu Dhabi, United Arab Emirates
American Community Schools, an English-speaking private school system in Athens, Greece
American Cooperative School of La Paz
American Cooperative School of Tunis
Anglo-Chinese School, Singapore, a group of Methodist schools in Singapore
Anglo-Chinese Schools, Malaysia, a group of Methodist schools in Malaysia
Arkansas Correctional School, a school system in prisons, in Arkansas
Associated Colleges of the South, a group of liberal arts colleges in the USA
Assumption College School, a catholic high school in Ontario, Canada
Aurora Christian Schools, a private PreK-12 school in Aurora, Illinois, USA
Avery Coonley School, a private elementary school in Downers Grove, Illinois, USA
Lehman Alternative Community School, a combined middle and high school Ithaca, New York

American Community Survey, a project of the US Census Bureau
Administration for Children's Services, governmental agency of New York City
Australian Customs Service, former Australian government agency for border protection, duties and taxes (1985–2009)

2-Amino-3-carboxymuconic semialdehyde, a chemical in tryptophan metabolism
Acetyl-CoA Synthetase, an enzyme
Acute compartment syndrome
Acute coronary syndrome, a form of chest pain due to reduced oxygen supply to the heart muscle
Advanced Cataract Surgery, the modern method of cataract removal using phacoemulsification
Alternate care site, a non-traditional medical treatment facility established in a public health crisis
Atriocaval shunt, a surgical procedure

Attack Characterization System
Aerial Common Sensor, a Lockheed Martin reconnaissance aircraft airframe for the US Army and Navy
Army Combat Shirt, flame-resistant shirt developed for the US Army
Auxiliary crane ship, a US Navy hull classification symbol
Cavalry Corps (Ireland) (1st Armoured Cavalry Squadron), an armoured reconnaissance unit of the Irish Army
ACS-3, the military version of Raybird-3, a Ukrainian UAV

Advanced Camera for Surveys, an instrument aboard the Hubble Space Telescope
Advanced Composite Solar Sail System (ACS3), a NASA technology demonstration for future small spacecraft
Air cavity system, a modern marine craft design concept based upon capturing air beneath a vessel's hull to reduce drag and increase speed and fuel efficiency
Anticenter shell, a supershell located outside of the galaxy
Attitude control system, a spacecraft system